xfce4-screensaver blanks screen multiple times while trying to unlock the screen

[spicemines]

When the screensaver activates and then locks the screen, whenever I move or click the mouse or tap a key, the screen shows the login prompt, but then immediately blanks again. This can happen anywhere from 1-10 times before the screen stops blanking, allowing me to type in my password to unlock the screen. This behavior only occurs when the screensaver and lock screen are activated in the Xfce Screensaver application. Deactivating the lockscreen in the Screensaver application causes this behavior to stop.

I have experienced this issue on a Dell Inspiron 7348 (Core i3-5010U, 4GB RAM, 120GB SSD) and in VirtualBox 7.

OS: Xubuntu Lunar Lobster (development branch) x86_64

xfce4-screensaver:
  Installed: 4.16.0-1
  Candidate: 4.16.0-1
  Version table:
 *** 4.16.0-1 500
        500 http://us.archive.ubuntu.com/ubuntu lunar/universe amd64 Packages
        100 /var/lib/dpkg/status

ProblemType: Bug
DistroRelease: Ubuntu 23.04
Package: xfce4-screensaver 4.16.0-1
ProcVersionSignature: Ubuntu 6.2.0-20.20-generic 6.2.6
Uname: Linux 6.2.0-20-generic x86_64
ApportVersion: 2.26.0-0ubuntu2
Architecture: amd64
CasperMD5CheckResult: pass
CurrentDesktop: XFCE
Date: Tue Apr 11 13:28:15 2023
InstallationDate: Installed on 2023-04-11 (0 days ago)
InstallationMedia: Xubuntu 23.04 "Lunar Lobster" - Daily amd64 (20230411)
SourcePackage: xfce4-screensaver
UpgradeStatus: No upgrade log present (probably fresh install)

[spicemines (spicemines)]

This behavior also occurs after rebooting the system.

[Ubuntu QA Website (ubuntuqa)]

This bug has been reported on the Ubuntu ISO testing tracker.

A list of all reports related to this bug can be found here:
https://iso.qa.ubuntu.com/qatracker/reports/bugs/2015922

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Ted Cabeen (ted-cabeen)]

I see the same behavior and also get the following kernel message:
[535542.199857] traps: xfce4-screensav[568256] general protection fault ip:5647b4378ef1 sp:7fff3c70ace0 error:0 in xfce4-screensaver-dialog[5647b436e000+e000]

[Ted Cabeen (ted-cabeen)]

Looks like this is an upstream bug, fixed in 4.18.0.

Here's the original issue with a first fix:
https://gitlab.xfce.org/apps/xfce4-screensaver/-/issues/119

And a second patch as well that actually fixes the main issue:
https://gitlab.xfce.org/apps/xfce4-screensaver/-/issues/116
https://gitlab.xfce.org/apps/xfce4-screensaver/-/merge_requests/22

Debian has 4.18.0 in salsa:
https://salsa.debian.org/xfce-extras-team/xfce4-screensaver
Installing this on Lunar resolves the problem.

[Kitserve (ubuntu-kitserve)]

For those who don't want to wait for the patch to be backported, and are also not keen on installing a newer version of the package from Debian, here are some notes on how to rebuild the package: https://kitson-consulting.co.uk/blog/fix-xubuntu-lunar-23.04-xfce4-screensaver-lock-screen-bug. The temporary package that results should automatically be overwritten by the next official repo version when it is released.

[Ivan Yosifov (iyosifov)]

Is there any timeline on this or way to bump the importance from "undecided"?
Seems more like a "release blocker" than "undecided".
What's the point of even having development branch testing if things like this are found but then just released as is?

[Doubletwist (doubletwist)]

Still hoping for a proper update on this issue. In the meantime, building a temporary package as described my Kitserve in comment #7 (https://bugs.launchpad.net/ubuntu/+source/xfce4-screensaver/+bug/2015922/comments/7) seems to have worked.

[Boris Gjenero (boris-gjenero)]

Wow, I thought there was something wrong with the video driver after wake, but it was just this bug. I fixed the problem by installing libxfce4ui-2-0_4.18.4-1 and xfce4-screensaver_4.18.2-1 from the next Ubuntu version, 23.10 Mantic:
https://packages.ubuntu.com/mantic/libxfce4ui-2-0
https://packages.ubuntu.com/mantic/xfce4-screensaver
I am disappointed that no fix was released for such a significant bug in such a long time, but at least I fixed this problem for myself.